Performance gains after LSD install?

[suss6052]

Originally Posted by Macky21

I thought the RS and RS500 used electronic torque vectoring? I remember Clarkson talking about it on the Top Gear episode

Nope, the RS used good old fashioned mechanical tuning (with a new suspension geometry to keep things in line via the revo-knuckle) and a quaife LSD.

Originally Posted by bigdesignmachine

So that would make my comment correct then.

Yeah, its not for the 2013+ Focus ST or the MMT6 gearbox, therfore there is not currently an off the shelf limited slip differential for these cars.

[bigdesignmachine]

Ok Glad to know Im not insane. I suppose if the original responder had noticed I specified a model and year for my question, then the response of Quaife making an LSD for the ST wouldnt have been given.

I swear....I feel like Im getting Craigslist responses sometimes. Im specific in my ask but I get off the wall responses / answers / questions.

[bigdesignmachine]

I got an email back from Quaife.

They verified that PT# QDF41Z which fits the Ford Mondeo ST220 will also fit the 2013 ST MMT6 gearbox.

These were the emails I got from Quaife

Dear Marty,

Thank you very much for your enquiry;
Yes it runs the QDF41Z.

If you have any further questions or I can be of any assistance in the future
please don't hesitate to contact me.

Kind regards
Dave King
Sales

Dear Marty,

Yes I can confrim that is correct.

Kind regards
Dave King
Sales

[bigdesignmachine]

So if you install an LSD does the ECU need to be reprogrammed to understand there is a limited slip differential being run between the axles instead of the open differential?

[Schroeder02]

I have installed LSD on several cars probably 6 to 8, the difference is tremendous. The most significant difference was when I installed it in my 07ST with a stock motor. I installed the diff prior to installing a turbo. I was amazed what a difference it made in just a stock car. When accelerating though a corner what I noticed was the car pulled though the corner, opposed to just going though the corner. I also installed a LSD on my svt track car that had been sc before I installed the diff. I didn’t have the same night and day reaction when I did the installation one that car but it could be due to the stiffer suspension and stickier tires. However it did really help with inside tire spin on tight corners.
There are several benefits to a diff, one the power the st has it really does not get out of the corners as quickly as it could. When I tracked mine last October the car was fighting for traction one of several tight corners. I know with a diff I would have picked up 5mph up the hill if I could have put the power down. Everyday benefit, traction, my 07 ST has a turbo and make 230 to the wheels it my dally driver, rain snow mud whatever. And the diff make a world of difference, I have a set of show tires on it and have never felt uneasy about driving that car in any winter condition. Even with the turbo if I brake the wheels loose it both wheels and very construable, it put that car against any 4wd car in bad weather.

As for you question regarding the ECU I’m not positive however my thought is it probably not going to have any real adverse affect on the car. The computer is most likely detecting the difference in wheel speed and then applying the brakes, the tq vectoring is detecting the car torque steering and correcting for that. The Diff will reduce both situation there for the computer needing less impute to correct. And if the ECU does go nuts I’m sure it could be adjusted or turned off in a tune.

[bigdesignmachine]

Originally Posted by Schroeder02

I have installed LSD on several cars probably 6 to 8, the difference is tremendous. The most significant difference was when I installed it in my 07ST with a stock motor. I installed the diff prior to installing a turbo. I was amazed what a difference it made in just a stock car. When accelerating though a corner what I noticed was the car pulled though the corner, opposed to just going though the corner. I also installed a LSD on my svt track car that had been sc before I installed the diff. I didn’t have the same night and day reaction when I did the installation one that car but it could be due to the stiffer suspension and stickier tires. However it did really help with inside tire spin on tight corners.
There are several benefits to a diff, one the power the st has it really does not get out of the corners as quickly as it could. When I tracked mine last October the car was fighting for traction one of several tight corners. I know with a diff I would have picked up 5mph up the hill if I could have put the power down. Everyday benefit, traction, my 07 ST has a turbo and make 230 to the wheels it my dally driver, rain snow mud whatever. And the diff make a world of difference, I have a set of show tires on it and have never felt uneasy about driving that car in any winter condition. Even with the turbo if I brake the wheels loose it both wheels and very construable, it put that car against any 4wd car in bad weather.

As for you question regarding the ECU I’m not positive however my thought is it probably not going to have any real adverse affect on the car. The computer is most likely detecting the difference in wheel speed and then applying the brakes, the tq vectoring is detecting the car torque steering and correcting for that. The Diff will reduce both situation there for the computer needing less impute to correct. And if the ECU does go nuts I’m sure it could be adjusted or turned off in a tune.

Schroeder02

Thanks for the examples and the explanation. I have read several different web sites regarding the LSD and how it works. I watched a really cool video that actually explained visually how the limited slip works and compared it to an open differential and even toyotas brake differential system.

I figured that the ECU would just see less difference between the wheels in turns and would just compensate less. So this makes me feel a little better! Not that I felt bad before hahaha

[Schroeder02]

Originally Posted by bigdesignmachine

Schroeder02

Thanks for the examples and the explanation. I have read several different web sites regarding the LSD and how it works. I watched a really cool video that actually explained visually how the limited slip works and compared it to an open differential and even toyotas brake differential system.

I figured that the ECU would just see less difference between the wheels in turns and would just compensate less. So this makes me feel a little better! Not that I felt bad before hahaha

If I can ever get my other project finished, I really want to pull the trans on the st and put a diff in it. Maybe this summer